Small hermetic compressor



Dec. 31, 1968 R. HINTZE SMALL HERMETIC COMPRESSOR Original Filed Jan. 4, 1965 United States Patent 0 3,419,207 SMALL HERMETIC COMPRESSOR Rudolf Hintze, Bernardstrasse 100, Offenbach (Main), Germany Continuation of application Ser. No. 423,264, Jan. 4, 1965. This application Sept. 13, 1966, Ser. No. 579,177 14 Claims. (Cl. 230-58) ABSTRACT OF THE DISCLOSURE A motor and compressor unit having a common shaft with a first axis is mounted in a tubular housing having a second axis intersecting the first axis so that the larger compressor stator is spaced from the housing the same minimum distance as the smaller motor stator.

The present application is a continuation application of my copending application Ser. No. 423,264, now abandoned.

The present invention relates to compressors and more particularly to motor-compressor units for refrigerators.

The object of this invention is to provide a very small motor-compressor of the socalled hermetic-type as used in home refrigerators. In the manufacture of such refrigerators, not only the exterior dimensions determine the actual food storage capacity in the interior, because also the space taken up by the motor-compressor in its housing detracts from the usable storage capacity. Therefore it is obvious that a small and spacesaving compressor will result in a relatively greater usable food capacity than a large one, if used in a refrigerator of the same exterior dimensions.

Furthermore a small and compact motor-compressor, assuming the same refrigerating capacity, will also save material as well as labor for its own manufacture and therefore allow the manufacturer to sell it at a lower and more competitive price.

Therefore, the principal objects of this invention are on the one hand to provide a motor-compressor far smaller than has heretofore been possible, and on the other hand to reduce material and production cost. Another object is to increase the food storage capacity of a refrigerator.

Motor-compressors of the hermetic type available in the market in general have a vertical crankshaft and because the axial dimension of the compressor has to be added to the axial dimension of the motor, to determine the height of the unit, a relatively fiat motor is used, resulting in a lower housing of the motor-compressor. But the flat motor has a greater diameter and requires more material for the compressor. Furthermore housing of the motor-compressor has to accommodate to the greater motor diameter resulting in a big and expensive unit.

It has been proposed to use a horizontal crankshaft to reduce the height of the motor-compressor unit. It is obvious, that in the horizontal direction there is enough place for any motor-compressor. While this considerable spacesaving was accomplished, the motor diameter was not reduced, because transverse compressor dimensions from the center of the crankshaft to the valve cover in the case of reciprocal piston compressors, are greater than the radius of the motor-stator.

It is, therefore, another object of this invention to position a motor-compressor unit inside a housing in such a manner that the dimensions of the housing are a mini mum while the motor-compressor unit is spaced the required minimum distances from the inner surface of the housing. In order to obtain an overall symmetrical spacing between the motor-compressor and the housing the axis of the main shaft is arranged at a certain angle to the main axis of the housing. The point of intersection of the two axes is preferably situated in the center of gravity of the motor.

Due to this arrangement the transverse dimension of the compressor has no influence on the diameter of the motor, which can be reduced.

With these objects in view, a motor-compressor unit according to the invention comprises a tubular housing having a first axis; a compressor and a motor located in said housing and respectively having a compressor stator and a motor stator secured to each other, and a common shaft having a second axis, the maximum radial extension of said motor stator transverse to said second axis being smaller than the maximum radial extension of said compressor stator transverse to said second axis; and supporting means for permanently supporting said compressor stator and said motor stator in said housing in a position in which said first and second axes intersect, and which the extremities of said compressor stator and of said motor stator are spaced substantially the same selected minimum distance from the inner surface of said housing.

It is also an object of the present invention that the cover for closing muffler chambers simultaneous serves as a second bearing for the crankshaft.

Another object of this invention is to utilize the short distance between a connecting rod of a compressor piston and the oil level, caused by the inclination of the crankshaft of the compressor, for a particular short oil spoon for not only splashing the oil but also guiding a stream of oil under slight pressure to the crank shaft bearing and further to the piston-pin, while the splashed oil dropping on the crankshaft is guided to the crankshaft-bearings by centrifugal force by means of the conical design of the shaft.

In accordance with this invention, the connection between the motor-stator and the compressor-body is formed by arc welding so as to avoid the additional space required by screw-fastening of the motor. This weldingconnection also results in a more accurate centering of the motor airgap and in fewer magnetic losses.

It is another object of this invention to provide means for dissipation of heat inspite of the reduced diameter and surface of the compressor housing by corrugating the housing material for increased absorption of heat by the housing inside and better dissipation at the outside.

A further object of this invention is an arrangement for assembling the motor-compressor unit. The motor-compressor is assembled with auxiliary parts outside of the housing and then inserted into it by means of a U-shaped member, which has before passed through the corresponding holes in the bottom of the housing.

Further objects, features and characteristics of the invention will be apparent from the following description of specific embodiments when read in connection with the accompanying drawings.

FIG. 1 is an axial sectional view of the motor-compressor in its housing.

FIG. 2 is a front view of the motor-compressor in its housing without the housing cover.

FIG. 3 is a horizontal sectional view, showing the motor-compressor in its housing with the upper half of this housing cut away.

Referring now to the FIGS. 1-3, it will be seen that the tubular housing 1, which may be corrugated as shown at 42 for better heat dissipation, surrounds the compressor 2 and its driving motor 3 spaced therefrom a symmetrical distance h, which is determined by the expansibility of springs 5, 6 and 7. Because the radius of the motor 3 is smaller than the overall transverse dimension of the compressor 2 from the crankshaft 8 to the valvecover 9, the axis of chankshaft 8 is arranged at a certain angle to the axes of the housing 1, which assures a symmetrical spacing between the inner surface of housing 1, and the valvecover 9 and all parts of the motor 3, the distance h determining the inner diameter of the housing 1. The intersection of the axes is in the point of gravity of the motor 3. The compressor stator and the motor stator are rigidly secured to each other by welding and form a common stator including a cast body 28 with feet 28:: to which the laminated motor stator 29 is welded. The common shaft 8 has a crank portion 8a for driving the compressor piston by connecting rod 17, and a motor shaft portion 8b. Since the maximum radial extension of the motor stator 29 is smaller than the maximum radial extension of the compressor stator including valve cover 9, shaft 8 and its axis are positioned in the housing at an angle to the housing axis so that the extremities of the common stator are spaced the same distances h from the housing 1. The axis of thetubular housing and the axis of shaft 8 are located in a vertical plane, and as best seen in FIG. 2, the compressor stator is unsymmetrical to another plane passing through the axis of shaft 8 perpendicularly to the aforesaid vertical plane. It is preferred to place the point of intersection of the two axes at the center of gravity of motor 3, since the motorcompressor unit is resiliently mounted on spring 5, 6, 7. Motor 3 has a winding 3:: which is spaced from housing 1 at least the distance it.

The muffier chambers 10, 11, 12 and 13 are situated in pairs on both sides of the cylinder 14 and support the compressor 2 on the springs and 6 and define together a space 16 to open opposite the oil sump s that the oil spoon 18, which is secured to the connecting rod 17, dips into the oil sump 15 during each revolution and splashes oil over the gear. The muffler cover 19 forms a bearing 20 for crankshaft 8.

The round oil spoon 18, which lifts, in together with a slot 21 in the undivided crank bearing of the connecting rod 17, the oil into the oil groove 22 of the crank so that oil passes through the oil hole 23 to the piston pin bearing 24. The bearings 25 and 20 of the crankshaft 8 are lubricated due to the action of the centrifugal force by the oil which is splashed over tha crankshaft S and guided to the bearings by the conical reduced portions 26 and 27 of crankshaft 8. The oil is also thrown by the shoulders of the crank against the piston and the cylinder 14 inside.

Motor 3 is welded to a common stator body 28, which is a casting forming the bearing 25, the cylinder 14 and the muffler chambers 10, 11, 12 and 13, eliminating the space required by the usual screw fastening. The rotor 29 is pressed onto a straight portion of crankshaft 8.

The suspension spring 7, situated on the motorside of the unit, is fastened to the motorstator by a member 30 and rests on the support 31, which is U-shaped and has a hole 32 receiving a shaft portion to limit the movement of the spring mounted motor-compressor and to avoid touching of the housing 1 by motor 3. The open end of U-shaped member 31 is connected with the transverse bracket 33 which has bent rojections 34- and 35, supporting the electric plug socket 36 and guiding it into conductive contact with the terminals 37 when the preassembled motor-compressor is inserted into the housing 1. The bracket 33 carries parallel suction and pressure tubes 38 and 39 of the compression. The tubes 38 and 39 project through holes 40 and 41 in the bottom of the housing, in which they are soldered after being inserted during the assembly so that supports 38, 31 is properly positioned in relation to the casing for supporting the compressor-motor unit on springs 5, 6, 7 spaced from the inner surface of the housing. Before the assembly, a U-shaped tool 100 is inserted through holes 40, 41 into the housing for guiding tubes 38, 39 thereon during the insertion of the motor-compressor unit.

It will be understood that this invention, which has in view smaller and more inexpensive hermetic compressors for refrigeration purposes, uses also many elements of already known design besides the described improvements to make up the complete compressor.

I claim:

1. A motor-compressor unit comprising, in combination, a tubular housing having a first axis; a compressor and a motor located in said housing and respectively having a compressor stator and a motor stator secured to each other, and a common shaft having a second axis, the maximum radial extension of said motor stator transverse to said second axis being smaller than the maximum radial extension of said compressor stator transverse to said second axis; and supporting means for permanently supporting said compressor stator and said motor stator in said housing in a position in which said first and second axes intersect, and which the extremities of said compressor stator and of said motor stator are spaced substantially the same selected minimum distance from the inner surface of said housing.

2. A motor-compressor unit according to claim 1 where-in said compressor stator is unsymmetrical to a first plane passing through said second axis perpendicularly to a second plane passing through said first and second axes, said extremity of said compressor stator being located in said second plane.

3. A motor-compressor unit according to claim 1 wherein said first and second axes intersect at a point located at the center of gravity of said motor stator.

4. A motor-compressor unit according to claim 1 wherein said compressor stator includes a body having bearing means for said shaft, a cylinder bore, open muffler chambers adjacent said cylinder bore, and a cover closing said mufiier chambers, said covering forming said extremity of said compressor stator; wherein said shaft has a crankshaft portion located in said compressor stator, and another shaft portion located in said motor stator, wherein said compressor includes a piston in said cylinder bore and a connecting rod connecting said crankshaft portion with said piston and having an oil spoon for lubricating purposes; and wherein said supporting means includes springs supporting said compressor stator and said motor stator in said position.

5. A motor-compressor unit according to claim 1 wherein said supporting means includes springs supporting said compressor stator and said motor stator; wherein said first and second axes intersect at a point located at the center of gravity of said motor stator, and wherein the diameter of said inner surface of said tubular housing is selected to be spaced said minimum distance from the point of maximum extension of said motor stator when the same oscillates about said center of gravity.

6. A motor-compressor unit according to claim 1 wherein said motor stator has flat portions, and wherein said compressor stator is located within the limits of said flat portions, wherein said tubular housing has flat portions and is shaped to provide at said fiat portions thereof said minimum distance from said fiat portions of said motor stator.

7. A motor-compressor unit according to claim 1 wherein said motor includes a winding projecting from said motor stator and being spaced from said inner surface of said tubular housing at least said minimum distance.

8. A motor-compressor unit according to claim 1 wherein said compressor stator includes a body casting; and wherein said motor stator is welded to said body casting.

9. A motor-compressor unit according to claim 8 wherein said body casting has supporting feet overlapping a part of said motor stator and being welded to the same.

19. A motor-compressing unit according to claim 1 wherein said compressor stator is formed with muflier chambers and includes a cover closing said mufiier chambers; and a bearing mounted on said cover for supporting said shaft.

11. A motor-compressor unit according to claim 1 wherein said compressor stator has an opening located above the bottom portion of said tubular housing and adapted to serve as an oil sump, and an oil spoon in said opening driven from said shaft and adapted to splash oil from said oil sump; wherein said compressor stator has mufller chambers; and wherein said supporting means includes springs abutting said mufller chambers and said housing and located on opposite sides of said opening.

12. A motor-compressor unit according to claim 11 wherein said compressor stator has a cylinder bore, wherein said compressor includes a piston located in said cylinder bore, wherein said shaft has a crankshaft portion located within said opening of said compressor stator for moving said piston in said cylinder, said crankshaft portion being tapered for moving oil by the centrifugal force, and having shoulders for throwing oil to said piston and cylinder, including bearing means for said crankshaft portion, and a connecting rod and piston pin connecting said piston with said crankshaft portion; and wherein said oil spoon is shaped for guiding the oil through a hole into said bearing means, said bearing means having a groove communicating with a duct in said connecting rod for supplying oil to the piston pin.

13. A motor-compressor unit according to claim 1 comprising a device for sliding the compressor and motor into said tubular housing and for securing it in the same, said device comprising a bracket, a motor spring suspension, and a member having a hole receiving a portion of said shaft for limiting the amplitude of oscillation of the same for preventing said motor stator from touching said housing; said bracket being adapted for holding a plug terminal for guiding it to a terminal when assembling said motor and compressor in said housing; two tubes fastened to said bracket and being arranged in parallel and serving as connections with suction and pressure lines, said tubes being soldered into holes at the bottom of said housing in the assembled condition of said motor-compressor unit, said tubes being adapted to be guided into said holes by a U-shaped tool.

14. A motor-compressor unit according to claim 1 wherein the inner surface and the outer surface of said housing are formed by a corrugated wall for providing an enlarged surface.

References Cited UNITED STATES PATENTS 2,628,016 2/1953 Higham 230-58 2,959,068 11/1960 Doeg 23058 XR FOREIGN PATENTS 1,145,295 3/1963 Germany.

920,787 3/1963 Great Britain.

ROBERT M. WALKER, Primary Examiner.

US. Cl. X.R. 230206, 235

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,419,207 December 31, 1968 Rudolf Hintze It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification, after line 6, insert Claims priority, application Germany, Jan. 15, 1964, H 51,377

Signed and sealed this 17th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

